Alloy of steel and method of treating the alloy



Jari. 14, 1930.` l c. P. rBEATH ET A1. 1,743,309

ALLOY OF STEEL AND METHOD OF TREATING THE ALLOY Ulea Nov. 19, 1927 ,Panarea aan. 14, 1930 UNI-TED STATES PATENT- OFFICE CHARLES PHILIP DEATH, F LA. GRANGE, AND BETHEL JAY BABBITT, 0F RIVERSIDE,v

. ILLINOIS,

ASSIGNORS T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y.,'A CORPORATION OF NEW YORK ALLOY-0F STEEL AND METHOD 0F TREATING THE ALLOY Application med November 19, 1927. .Serial No. 234,838.

This invention relates to an alloy of steel I and a method of treating the alloy, and more particularly to a magnet steel alloy and a method of heat treating the alloy.

The objects of the invention are to provide a magnet steel having a high remanence and coercive force and an-ixnproved method of treating the magnet steel. i

In accordance with the general features of the invention, the magnet steel consists chiefly of the ferrous metals comprising iron, cobalt, and nickel which may be magnetically hardened to obtain a high coercive force and magnetic remanence by heating the steel for a prolonged period and then quenching the steel at a temperature not in excess of 1550 F. Ores containing cobalt in many cases also contain considerable quantities of nickel, iron and carbon. It has been found that a high quality of magnet steel having the required remanence and coercive lforce can be roduced Without fully refining such ores y removing certain constituents and adding others and subjecting the resulting alloy to an appropriate heat treatment.

For an illustration of the characteristics of the magnet steel of this invention reference may be had to the accompanying drawing in which the single figure graphically represents the improvementof the magnetic properties of the steel upon a prolonged heat treatment. The abscissas inthe figure represent hardening temperatures and the ordinates for the maximum andresidual induction indicated at the left side of the figure represent magnetic induction in maxwells per square centimeter, While the ordinates for coercive force indicated at the right side of the figure represent the magnetlc coercive force in gilberts per centime-ter. l

Curve 2 represents the maximum induction of a specimen of magnet steel of this invention showing the specimen to have a maximum induction when hardened at a temperature in the vicinityl of 1550 F. Curve 3 represents the maxium induction of a similar specimen after retainingit at the hardening temperature for two or three hours before quenching. It will be noted that the prolonged heating of the specimen reduces thebut even more pronounced effect of the pro-v -longed heating is had upon the magnetick remanence of the steel as may be seen from curves 4 and 5 representing the residual mag. netic induction o a specimen not heat treated and a heat treated specimen respectively.l The curve of the heat treated specimen shows that its residual magnetism isv from 800 to 1000 maxwells per square centimeter greater than the residual magnetism of the specimen which has not been heat treated, and since residual magnetism determines the strength of a permanent magnet this eect is of considerable importance.

The curves 6 and'7 show the eflect of the heat treatment upon the coercive force of the steel. In contrast to the maximum and residual induction the hardening temperature is slightly greater for a given coercive force and the coercive force is slightlydecreased n in the heat treated specimen until-the curves manganese 2.5%, carbon .8%, nickel 7% and 60.7% iron. ,These proportions may be varied to some extent, and the alloy Will still retain its essential characteristics. Thus the cobalt content may be varied from 5 to 50%, the tungsten content from 1 to 12%, the manganese content from 0 to,7%, the carbon content from .3 to 5%, and thenickel content from 6 to 18%. The alloy may also .con-

tain chromium from 0 to`12%.

The nickel content of this alloy has anim portant eii'ect in its heat treatment. -Many steels depreciate considerably Wheny .exposed to high temperaturesfor an extended time. As pointed out above the magnetic charac-l teristicsof the steel of this invention improve sol . when the is retained at a-high temperature for several hours.

partsto it the desired magnetic characterisl 12%, and ir'on.

tics of possessing a high coercive force and magnetic remanence. A

It will be understood that the embodiments of the invention herein described and illustr'ated are merely representative forms of the invention which is capable of many other modifications without departing from thev spirit of the invention.

What is claimed is: 1. A magnet steel alloy comprising cobalt 1,74a,soo

halt-nickel steel, which consists of heating a steel containing approximatelyl 20% cobalt, 9% tungsten, 2.5% manganese, .8% carbo 7% nickel and 60.7% iron to a temperature above the A2 transformation point, retainin the temperature at approximately 1500 n.

steel.

for two to three hours, and quenching the In witness whereof, we hereunto subscribe this 7th day of November A. D.,

CHARLES PHILIP BEATH. BETHEL JAY BABBITT.

our names 1927.

5-50%, tungsten 1-12%, manganese (lf-,7%,

carbon .3-5%, nickel 5-18%, chromium 0- 2. A magnet steel alloy comprising cobalt 20%, tungsten 9%, manganese 2.5%, carbon .8%, nickel 7%, and iron 60.7

3. A method of improving the magnetic properties of a cobalt-nickel steel, which consists of heating a steel containing 5 to 50% cobalt and 5 to 18% nickel to a temperature above the A2 transformation point,y allow- `fans ing the steel to cool to a temperature of approzldmately 1500 F., and quenching the stee 4. A method of improving the magnetic properties of a cobalt-'nickel steel, which consists of heating a steel containing 5 to .50% cobalt and 5 to 18% nickel to a temperature above the A2 transformation point, retaining the temperature at from 1500 to 1550 F. for several hours, and quenching the steel.

5. A method ofproducing a high coercive force land a high magnetic remanence in a cobalt-nickel steel, which consists of heating a steel containing 5 to 50% cobalt and 5 to 18% nickel to a temperature above the A2 transformation point, retaining the temperatur'e at approximately 1500 E. for two to three hours, and quenching the steel.

6. A method of producing a high coercive force and high magnetic remanence in a c0- balt-nickel steel, which consists of heating a steel containing 5 to 50% cobalt, 1 to 12% tungsten, 0 to 7% manganese, .3 to 5% carbon, 5to 18% nickel, 0 to 12% chromium and the remainder principally iron, to a temperaf ture above the A2 transformation point, al# lowing the steel to cool to a temperature of approximately 1500 F., and quenching the steel. v e.

7. A method of producing a highcoercive force and high magnetic remanence in a cov:as 

